It has long been recognized that compressed gas cylinders, used widely today in industry, construction, repair service facilities and hospitals, represent a hazard to life and property with numerous safety codes and regulations governing their storage, transportation, and use. Unchecked gas flow from a highly pressurized cylinder can turn the cylinder into a deadly destructive projectile, as well as suddenly release a large volume of gas into the ambient air which may be of a hazardous character in itself.
Good safety practices require cylinders containing combustible compressed gases to be stored in "out" buildings or in areas remote from populated sites to minimize their danger and that compressed gas cylinders be chained down while being transported, both on a delivery truck and on a shop dolly during use. This is to minimize the possibilities of upset and damage to the cylinders and their highpressure control valves. Further, when the cylinders are not in use, a valve-protector-cap is attached to the cylinder, over the control valve to guard against damage thereto. However, when the cylinders are placed in use, the protector-cap must be removed to gain access to the control valve for connecting the usual pressure regulator valves or to make other operative connections thereto.
The compressed gas cylinders are usually made of drawn steel without seams and are carefully heat-trusted so as to develop great strength and toughness. Further, frangible disks are incorporated into the high-pressure control valves to relieve overpressurization generally associated with compressed gas cylinders exposed to elevated temperatures. This does not, however, afford any protection against a sudden "blow-out" of gas due to a damaged control valve.
In the event the high-pressure control valve is damaged, as for example by a fork lift truck maneuvering too close to a gas cylinder, or an over-head crane moving material in the vicinity of a cylinder; or even by an upset or dropping of the cylinder, the top portion of the cylinder may be sheared away or severely cracked so that a jet stream of escaping gas from the broken control valve transforms the cylinder into a flying missile.
Since the control valve is the "weakest link" of the compressed gas cylinder assembly, great care must be exercised to prevent damage thereto while the gas cylinder is being used. However, carelessness or unavoidable accidents can cause damage to the control valve with disastrous consequences.